The Web Application Hacker’s Handbook Discovering and Exploiting Security Flaws

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Chapter 7 

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Attacking Session Management

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97C4EB6A

FF97C4EB6A

FF97C4EB6A

which immediately reveals the concealed pattern. The algorithm used to gen-

erate tokens adds 0x97C4EB6A to the previous value, truncates the result to a

32-bit number, and Base64-encodes this binary data to allow it to be trans-

ported using the text-based protocol HTTP. Using this knowledge, you can

easily write a script to produce the series of tokens that the server will next

produce, and the series that it produced prior to the captured sample.